... in favor of using the preemptable flavors of the respective
functions.
Signed-off-by: Jan Beulich <jbeulich@xxxxxxxxxx>
Index: 2008-10-27/xen/arch/x86/domain.c
===================================================================
--- 2008-10-27.orig/xen/arch/x86/domain.c 2008-10-29 17:10:03.000000000
+0100
+++ 2008-10-27/xen/arch/x86/domain.c 2008-10-29 17:10:41.000000000 +0100
@@ -1639,32 +1639,23 @@ static int relinquish_memory(
}
if ( test_and_clear_bit(_PGT_pinned, &page->u.inuse.type_info) )
- put_page_and_type(page);
+ ret = put_page_and_type_preemptible(page, 1);
+ switch ( ret )
+ {
+ case 0:
+ break;
+ case -EAGAIN:
+ case -EINTR:
+ set_bit(_PGT_pinned, &page->u.inuse.type_info);
+ put_page(page);
+ goto out;
+ default:
+ BUG();
+ }
if ( test_and_clear_bit(_PGC_allocated, &page->count_info) )
put_page(page);
-#ifdef DOMAIN_DESTRUCT_AVOID_RECURSION
- /*
- * Forcibly drop reference counts of page tables above top most (which
- * were skipped to prevent long latencies due to deep recursion - see
- * the special treatment in free_lX_table()).
- */
- y = page->u.inuse.type_info;
- if ( (type < PGT_root_page_table) &&
- unlikely(((y + PGT_type_mask) &
- (PGT_type_mask|PGT_validated)) == type) )
- {
- BUG_ON((y & PGT_count_mask) >=
- (page->count_info & PGC_count_mask));
- while ( y & PGT_count_mask )
- {
- put_page_and_type(page);
- y = page->u.inuse.type_info;
- }
- }
-#endif
-
/*
* Forcibly invalidate top-most, still valid page tables at this point
* to break circular 'linear page table' references as well as clean up
@@ -1685,8 +1676,23 @@ static int relinquish_memory(
x & ~(PGT_validated|PGT_partial));
if ( likely(y == x) )
{
- if ( free_page_type(page, x, 0) != 0 )
+ /* No need for atomic update of type_info here: noone else
updates it. */
+ switch ( ret = free_page_type(page, x, 1) )
+ {
+ case 0:
+ break;
+ case -EINTR:
+ page->u.inuse.type_info |= PGT_validated;
+ put_page(page);
+ ret = -EAGAIN;
+ goto out;
+ case -EAGAIN:
+ page->u.inuse.type_info |= PGT_partial;
+ put_page(page);
+ goto out;
+ default:
BUG();
+ }
if ( x & PGT_partial )
page->u.inuse.type_info--;
break;
@@ -1833,11 +1839,6 @@ int domain_relinquish_resources(struct d
/* fallthrough */
case RELMEM_done:
-#ifdef DOMAIN_DESTRUCT_AVOID_RECURSION
- ret = relinquish_memory(d, &d->page_list, PGT_l1_page_table);
- if ( ret )
- return ret;
-#endif
break;
default:
Index: 2008-10-27/xen/arch/x86/mm.c
===================================================================
--- 2008-10-27.orig/xen/arch/x86/mm.c 2008-10-28 14:42:09.000000000 +0100
+++ 2008-10-27/xen/arch/x86/mm.c 2008-10-28 14:53:16.000000000 +0100
@@ -1343,7 +1343,7 @@ static void free_l1_table(struct page_in
static int free_l2_table(struct page_info *page, int preemptible)
{
-#if defined(CONFIG_COMPAT) || defined(DOMAIN_DESTRUCT_AVOID_RECURSION)
+#ifdef CONFIG_COMPAT
struct domain *d = page_get_owner(page);
#endif
unsigned long pfn = page_to_mfn(page);
@@ -1351,11 +1351,6 @@ static int free_l2_table(struct page_inf
unsigned int i = page->nr_validated_ptes - 1;
int err = 0;
-#ifdef DOMAIN_DESTRUCT_AVOID_RECURSION
- if ( d->arch.relmem == RELMEM_l3 )
- return 0;
-#endif
-
pl2e = map_domain_page(pfn);
ASSERT(page->nr_validated_ptes);
@@ -1385,11 +1380,6 @@ static int free_l3_table(struct page_inf
unsigned int i = page->nr_validated_ptes - !page->partial_pte;
int rc = 0;
-#ifdef DOMAIN_DESTRUCT_AVOID_RECURSION
- if ( d->arch.relmem == RELMEM_l4 )
- return 0;
-#endif
-
pl3e = map_domain_page(pfn);
do {
Index: 2008-10-27/xen/include/asm-x86/config.h
===================================================================
--- 2008-10-27.orig/xen/include/asm-x86/config.h 2008-10-29
17:09:06.000000000 +0100
+++ 2008-10-27/xen/include/asm-x86/config.h 2008-10-28 14:53:16.000000000
+0100
@@ -41,14 +41,6 @@
#define CONFIG_HOTPLUG 1
#define CONFIG_HOTPLUG_CPU 1
-/*
- * Avoid deep recursion when tearing down pagetables during domain destruction,
- * causing dom0 to become unresponsive and Xen to miss time-critical softirq
- * deadlines. This will ultimately be replaced by built-in preemptibility of
- * get_page_type().
- */
-#define DOMAIN_DESTRUCT_AVOID_RECURSION 1
-
#define HZ 100
#define OPT_CONSOLE_STR "vga"
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